Poly-3, 3-bis(chloromethyl)oxetane containing isocyanates as adhesion improving agents



United States Patent 3,337,478 POLY-3,3-BIS(CHLOROMETHYL)OXETANE CON-TAINING ISOCYANATES AS ADHESION IM- PROVING AGENTS Douglas S. Richart,Reading, Pa., assignor to The Polymer Corporation, a corporation ofPennsylvania 0 Drawing. Continuation of application Ser. No. 478,414,Aug. 9, 1965. This application Aug. 19, 1966, Ser. No. 573,724

4 Claims. (Cl. 260-2) This application is a continuation of applicationSer. No. 478,414, filed Aug. 9, 1965, now abandoned, which in turn was adivisional application of my co-pending ap plication Ser. No. 218,104,filed Aug. 20, 1962, now abandoned, and relates to improved polymericmaterials and, more particularly, to coating materials having improvedadhesion to substrates.

The coating materials with which this invention is concerned are thechlorinated polyethers polymerized from 3,3-bis(chloromethyl)oxetanewhich results in the following molecular structure:

The preparation of this polymer is disclosed in detail, for example, inUS. Patent 2,722,340, and it is sold under the trademark Penton byHercules Powder Company. These resins have excellent resistance toattack by most corrosive chemicals and organic solvents and are,therefore, useful as coating materials for various processing equipmentsuch as tanks, reaction vessels, pipe lines and the like, wherecorrosion may be a problem.

Quality coatings for the protection of metal articles from corrosionshould be tightly adhered to the article. When coating articles by meansof various heat fusion coating processes with the polyether resins withwhich this invention is concerned, poor maintenance of adhesion underadverse service conditions is generally observed. Conventional primersdo not improve the results, probably due to the chemical inertness ofthe polyether resin. Present methods for providing prolonged adhesion ofthese resins to the substrate under adverse service conditions usuallyrely upon mechanical bonding or interlocking as can be achieved bychemically etching or sandblasting the surface of the substrate, butthese techniques leave much to be desired.

Accordingly, it is the object of this invention to provide polyethercoating resins that will adhere tightly to the substrates to which theyare applied.

Briefly, the object of this invention is achieved by mixing certainchemical compounds into the polyethers with which this invention isconcerned. Greatly improved adhesion is observed when minor quantities(from about A to about of certain compounds selected from the classconsisting of nitrogen-containing compounds, anhydrides,phenol/aldehydes and urea/aldehydes are mixed with these resins.

In the following examples, steel panels 1" x 4" x 45" were thoroughlycleaned by sandblasting and then coated with the chlorinated polyethersold under the trade name Penton to which the indicated compounds weremixed. (All percentages are by weight.) In Examples I to IV, the panelswere coated in a fluidized bed of the prepared resin by heating thepanels for-ZO minutes at 600 F., immersing them in the fluidized bed forabout 10-20 seconds and then placing them in a postheat oven at 525 F.for about 4 minutes. A smooth continuous film of about to mils was fuseduniformly over the surface of the panels.

The comparative degree of adhesion was determined by placing the samplesso obtained in boiling water and measuring the time until adhesion hadbeen lost to such .an extent that a knife blade'could be inserted underthe coating and the coating lifted away from the substrate. It was alsodetermined by coating control samples that loss of adhesion normallyoccurs in 4 hours or less if none of the compounds are mixed with thepolyether resin.

Example I 0.5% methylene bis(4-phenyl-isocyanate) (trademark Hylene M byDu Pont de Nemours & Co.) was added to the polyether resin. Adhesion waslost after 4 hours in boiling water. When 1% and 4% of this additive wasincluded, adhesion was maintained for 20 days.

Example 11 Example 111 3,3-dimethoxy 4,4-biphenylenediisocyanate (DADI)was added to the chlorinated polyether. Good adhesion was maintained for49 days.

Example IV 3,3"- dimethyl 4,4 biphenylenediisocyanate (TODI) was addedto the chlorinated polyether. Good adhesion was maintained for days.

Example V 50 parts of finely divided polyether resin (Penton) modifiedwith 3% of the his phenol adduct of methylene bis(4-phenyl-isocyanate inwhich the phenol is adducted to block or inactivate the isocyanategroups) (trademark Hylene MP by Du Pont de Nemours & Co.) were mixedwith 50 parts of a blend of 3 parts by volume trichloroethylene and 1part by volume of methylene chloride to form a suspension. A similarsuspension was prepared with unmodified chlorinated polyether resin.

4" x 1" X As steel panels were sandblasted to remove all dirt and greaseand coated with each of the above suspensions using a spray gun. Afterthe solvent carrier had evaporated, the panels, coated with a looselyadherent layer of powdered material, were baked for 5-10 minutes at 600F. to fuse the powdered coating into a continuous film. These coatingswere evaluated for retention of adhesion using the boiling water test.The unmodified coating lost adhesion in four hours or less. Thechlorinated polyether coating modified with 3% of the phenol adduct ofmethylene bis(4-phenyl-isocyanate) maintained adhesion for 21 days.

I claim:

1. An adherent coating composition comprised of a major portion of aresinous binder of a chlorinated polyether prepared from3,3-bis(chloromethyl)oxetane having the recurring structure:

and from about A to about 10% by weight of methylenebis(4-phenylisocyanate).

2. An adherent coating composition comprised of a major portion of aresinous binder of a chlorinated poly- 3 ether prepared from3,3-bis(chloromethyl)oxetane having the recurring structure:

(lJHiol OCHCCH CHzCl and from about to about 10% by Weight of 3,3-

dimethyl-4,4-biphenylenediisocyanate.

4. An adherent coating composition comprised of a major portion of aresinous binder of a chlorinated polyether prepared from3,3-bis(chloromethyDoxetane having the recurring structure:

and from about A% to about 10% by weight of the bis phenol adduct ofmethylene bis(4-phenylisocyanate) in which the phenol is adducted toblock the isocyanate groups.

References Cited UNITED STATES PATENTS 2,722,487 11/1955 McTigUe 26022,950,307 8/1960 France et a1 260453 3,089,783 5/1963 Carlson 2602 OTHERREFERENCES Hylene M. Hylene M50, Organic Isocyanates, Du Pont ElastomerChemicals Dept., publication No. HR-S January 1960. 3-,

Hylene MP, Water Stable Diisocyanate Generator,,Du Pout ElastomerChemicals Dept., publication No. HR-ZS (July 1957). I

SAMUEL H. BLECH, Primary Examiner.

1. AN ADHERENT COATING COMPOSITION COMPRISED OF A MAJOR PORTION OF ARESINOUS BINDER OF A CHLORINATED POLYETHER PREPARED FROM3,3-BIS(CHLOROMETHYL)OXETANE HAVING THE RECURRING STRUCTURE.